describe how to prepare a solution


Describe how you would prepare 1.0L of 0.20M (molar) NaCl from a 2.5M stock solution


-I have no idea what the hell a stock solution even is!

A stock solution is a more concentrated solution from which less concentrated solutions can be made. eg if you had a 4M solution and wanted to make 1L of 1M solution you would take 250mL of the stock solution and top it up to 1L in a standard flask using pure water. This is a 4x dilution.

To help work out the volumes needed use V1M1 = V2M2 where V1 is the volume of stock solution with a molarity (M1) of 2.5M and V2 and M2 refer to the diluted solution.

V1 x 2.5 = 1L x 0.2, so V1 = (1 x 0.2)/2.5 = 0.08L. So you need to take 0.08L or 80mL of the stock solution, put it in a 1L standard (volumetric) flask and make it up to 1L with pure water. Stopper and mix thoroughly.

'Chemistry is not just the study of matter; Chemistry is the study which matters!' - Kingchemist